1. Field of the Invention
The present invention relates to a semiconductor burn-in process and, more particularly, to an apparatus for inserting, removing, and sorting semiconductor devices according to the results of tests.
2. Description of the Related Art
In order to identify devices that are likely to fail in their early life, semiconductor devices after fabrication undergo testing or screening that applies electrical and thermal stresses to the devices and identifies devices having the potential for early failure. Generally, a process for screening the semiconductor devices is called a "semiconductor device burn-in test."
A monitoring burn-in test (MBT) chamber for the burn-in tests requires a semiconductor device handling and sorting apparatus or system which sorts semiconductor devices in accordance with the burn-in test results. The apparatus inserts semiconductor devices into a burn-in board for testing, removes tested semiconductor devices from the burn-in board, and sorts the tested semiconductor devices into good and failed categories. Such an apparatus typically includes various tools for rapidly performing the sorting operation.
For example, one conventional device handling and sorting apparatus includes a centering pocket unit, a DC test unit and a carrier pocket unit disposed in line on a stage of the apparatus. A burn-in board containing tested semiconductor devices thereon is disposed under the stage. A center portion of the stage has an opening so that the burn-in board moving in an XY-plane under the stage can be accessed through the opening. Thus, the burn-in board can be smoothly positioned for operations connected with various tools on the stage. Multiple transportation tools, which are driven by a driving cylinder, are in respective upper portions of the centering pocket unit, the DC test unit and the carrier pocket unit. The transportation tools transport the semiconductor devices rapidly and stably between the units.
In the conventional apparatuses such as described above, when a burn-in board having the burn-in tested semiconductor devices thereon is loaded to a lower portion of a stage, a transportation tool removes the semiconductor devices from the burn-in board and loads the semiconductor devices on the carrier pocket unit. From the carrier pocket unit, the transportation tool transports only good devices to an unloading tray positioned at an unloading terminal unit. Then, the carrier pocket unit which contains the remaining failed devices moves toward a rear portion of the stage, sorts the remaining failed devices into several levels, and loads the devices on burn-in rejecting trays according to the levels.
In order to prepare a semiconductor device for a burn-in test, a transportation tool loads the semiconductor device from a loading tray on a loading terminal to the centering pocket unit, aligns the semiconductor device, and transports the aligned semiconductor device to a DC test unit for a DC test of the semiconductor device prior to inserting the semiconductor device into a burn-in board. If the semiconductor device passes the DC test, the transportation tool plugs the semiconductor device into the burn-in board. However, if the semiconductor device fails the DC test, the transportation tool loads the semiconductor device into a DC rejecting tray. The DC rejecting tray is in the vicinity of an XY-table positioned under the stage, and moves in XY-plane under the stage so as to receive the DC test-rejected semiconductor devices.
To summarize, after unloading and sorting the semiconductor devices that are burn-in tested in the MBT chamber, the device handling and sorting apparatus loads semiconductor devices that passed the DC-test into an empty burn-in board and transports the burn-in board loaded with semiconductor devices to the MBT chamber for a new burn-in test.
Conventional device handling and sorting apparatuses have some problems. For example, burn-in tests and sorting of the semiconductor devices into good product or failures according to the results of the DC test are performed simultaneously. Therefore, respective tools related to good devices and rejected devices can collide because the tools move on the same operation line. In addition, an operation of the burn-in rejecting trays requires an XY-robot in addition to a robot that operates the transporting tools. The use of the two robots may complicate control of the apparatus, so that unexpected operation errors may occur. Moreover, operation of the DC rejecting trays may aggravate the operation errors. If the XY-table moves too frequently, a small impact can pop the semiconductor devices in the DC rejecting trays out of the DC rejecting trays. Further, a transportation tool may wait for a considerable time above the stage until the DC rejecting trays are properly positioned. As a result, overall operating efficiency of the apparatus is lowered.